In the transformation of a substance, for example, transformation of graphite to diamond, it is generally required to compress the original substance under superhigh pressure and at high temperature. In order to attain such a condition, the conventional art has employed static compression and heating simultaneously. However, this method has proved disadvantageous in that members subjected to the required high pressure are often damaged and moveover such a superhigh pressure cannot readily be produced.
There has been proposed another method, in which a solid body is impacted against a workpiece at a supersonic speed to produce shock waves in the workpiece; the resultant superhigh pressure and high temperature are utilized for transformation of the substance of the workpiece. In order to accelerate the solid body to such a high speed, the conventional method has utilized explosive substances. However, this method is not suited for practice in a factory, because the handling of explosives is dangerous and moreover noise, vibration and detrimental combustion gases are produced. Further, this method has not been satisfactory in that it is difficult to control the impact speed with suitable accuracy. In order to overcome these difficulties of the prior art method, a further prior art method has been proposed, in which a high-pressure gas stored in a reservoir is used as a power source. However, this method also has many problems in practical use, since a gas compressor for producing such a high pressure is very expensive, and further, storage of a high-pressure gas is accompanied with danger.